This invention relates generally to the navigation of a moving vehicle. In particular this invention relates to a method and system of indicating a direction of traffic flow for a one-way street.
Geographical Information System (GIS) databases continue to be vastly used to visualize coordinates and maps of streets at various locations. For example such a database may include existing directions and coordinates for the entire United States which may be provided by different road data providers. Roads on these maps are usually provided by two points (nodes) and a line connecting these two points is drawn. Referencing nodes toward each other indicates the direction of travel.
These databases prove very useful for large companies specializing in providing road directions to consumers. Vehicles having an onboard database and a processor capable of generating maps on its own can also take advantage of these databases. After the loading of the database a user is able to visualize the road map system of interest. In conventional GIS database loading methods, however, a user is able to visualize a map of a one-way street, but is unable to know which way the traffic flows along that one-way street.
One alternative is the use of properly digitized data. If the data is digitized in the direction of traffic flow, wherein the nodes are referenced towards each other properly, then arrows can be assigned to indicate the direction of traffic flow. Unfortunately, road data providers do not typically digitize the data in the direction of travel. Instead, these providers supply the road data with certain attributes that in conjunction with database rules provide the direction of travel. These attributes may include road lines, direction of travel attributes associated with these lines, and rules to understand these attributes. This type of road data cannot be displayed with arrows and thus a user cannot visualize the direction of traffic flow on the map.
This information is critical for a vehicle traveling on a one-way street, as well as an advisor directing a vehicle along a visualized map.
It is therefore desirable to provide a method to indicate the direction of traffic flow along a one-way street that overcomes the above disadvantages.
One aspect of the present invention provides a method of indicating road direction for vehicle instruction for a one-way street. A road database is provided and includes at least one start point and at least one end point to indicate a portion of the road. A center point is determined between the start and end point. A compass bearing is determined from the center point based on the position of the start point and end point. An angle of orientation indicator based on the compass bearing of the center point is determined.
An arrow symbol may be associated to the compass bearing and to the corresponding angle of orientation to indicate the direction of traffic flow. The associated arrow symbol may be stored in an arrow symbol database. It may be determined whether a distance between the start point and the end point does not exceed a distance tolerance value. An elapsed time between an initiating point in time when the start point and end point are selected and a terminating point in time when the angle of orientation is determined may be calculated.
The method may also comprise of determining a center point between the start and the end point. The compass bearing determination may comprise of determining the compass bearing of the center point based on the coordinates of the start and end point. The determined start point, center point, and bearing attributes may be stored into at least one file database.
When the start and end points are nodes on a line, the compass bearing determination may comprise of determining the compass bearing of the center point based on the nodes, a direction of travel attribute for the line, and road database rules. The determined bearing attributes and center point may be stored into at least one output file database.
Another aspect of the invention provides a navigation system for indicating road direction for vehicle instruction for a one-way street. The system includes means for providing at least one start point and at least one end point to indicate a portion of the road. The system also provides means for determining a center point between the start and end point. The system also provides means for determining a compass bearing based on the position of the start and end point. The system also provides means for determining an angle of orientation indicator based on the compass bearing of the center point.
The system may include means for associating an arrow symbol to the compass bearing and the corresponding angle of orientation to indicate the direction of traffic flow. The system may also include means for determining whether a distance between the start point and the end point does not exceed a distance tolerance value. The system may also include means for calculating an elapsed time between an initiating point in time when the start and the end point are selected and a terminating point in time when the angle of orientation is determined. The system may also include means for determining the compass bearing of the center point based on the coordinates of the start and end point. When the start and end points are nodes on a line the system may provide means for determining the compass bearing by determining the compass bearing of the center point based on the nodes, a direction of travel attribute for the line, and road database rules.
Another aspect of the invention provides a computer usable medium including a program for generating navigation instructions for a vehicle indicating road direction for a one-way street. The medium includes computer readable program code that provides a road database that includes at least one start and end point to indicate a portion of the road. The medium also includes computer readable program code that determines a center point between the start and end point. The medium also includes computer readable program code that determines a compass bearing from the center point based on the position of the start and end point. The medium also includes computer readable program code that determines the angle of orientation indicator based on the compass bearing of the center point.
The medium may include computer readable program code that associates an arrow symbol to the compass bearing and the corresponding angle of orientation to indicate the direction of traffic flow. The medium may also include computer readable program code that stores the arrow symbol in an arrow symbol database. The medium may also determine whether the distance between the start point and the end point does not exceed a distance tolerance value. The medium may include computer readable program code that calculates an elapsed time between an initiating point in time when the start and end points are selected and a terminating point in time when the angle of orientation is determined.
If the determination of the compass bearing comprises of determining the compass bearing of the center point based on the coordinates of the start and end point the medium may provide computer readable program code that determines the compass bearing of the center point. The medium may also provide computer readable program code that saves the start point with bearing attributes into at least one file database.
If the start and end points are nodes on a line the medium may provide computer readable program code that determines the compass bearing of the center point based on the nodes, a direction of travel attribute for the line, and road database rules. The medium may also provide computer readable program code that saves the at least one center point with bearing attributes into at least one output file database.
The foregoing and other features and advantages of the invention will become further apparent from the following detailed description of the presently preferred embodiment, read in conjunction with the accompanying drawings. The detailed description and drawings are merely illustrative of the invention rather than limiting, the scope of the invention being defined by the appended claims and equivalents thereof.